US1717820A - Compound for use in casting metals - Google Patents

Description

Patented June 18,

TES

1,717,820 PATENT. orrics.

BENJAMIN F. WALLACE, 0F BROOKLYN, NEW YORK.

No Drawing.

COMPOUND FOR USE IN CASTING METALS."

Application filed July 15,

This invention relates to the production of a so-called parting compound for employment in the casting of metals in order to effect a clean separation of thepattern from the sand surface in the mold, and has for its particular objects the is economical to manufacture pound which production of a comand use, highly eflicient, as well as possessing other advantages as hereinafter set forth.

For many years it has been customary in the foundry industry to employ dry parting powders approximating 200 mesh in fineness,

which powders were and surrounding sand cope and'the drag. These par-tin commonly consisted of a silicious dusted upon the pattern surfaces between the powders base, such.

as Tripoli rock, which is well known as essentially a natural decomposed silicapvith which were incorporated varying percentages of vegetable oils, tallow, stearic acid and the like,

by subjecting the mixture period of time to a sufficient heat tively short thereof for a rela-- to cause the oil or fatty vehicle to become distributed over the surface of the particles and to thoroughly penetrate the same, where-;

by the resultant material becomes waterproof and will float for short periods of time on the water.

The common test to determine when the heating operation is complete'is to take test portions sprinkle the same on of the material and the surface of the water and if the same do not immediately sink upon the agitation of the water but it is only with difficulty that the surface tension of the particles is upset or affected with the resultant sinking of the particles,

then it is recognized that the heating operation has been completed. Furthermore,

the more impervious the mixture is to moisture and the more resistant such mixture is to having its surface tension affected when the same is floating on water and. the surface agitated, the better the material is regarded for the purpose of effecting a perfect separation between the pattern andthe sand in the molding.

operation of foundry The aforesaid Tripoli rock has been con sidered as that it is highly and thus rapidly product possessing the sion and water-repellent properties.

an ideal base absorbent to fats and 011s becomes converted into a because of I the fact necessary surface ten- These prior partings, whether having a Tripoli base or other similar base, heavy as compared wi were relatively very th my hereinafter de- 1925. Serial No. 43,842.

scribed product. For example, a barrel the and the method of making the same, the fol-- lowing is set forth:

Precipitated calcium carbonate, which is a base that is ideally adapted for the production of parting because of its extreme fineness, its high grease and oil absorptive properties, and its extreme lightness, as well as because of the fact that the same constitutes a waste product in many industries, is first introduced while in a dry condition into a batch mixer, which latter is preferably provided with a suitable mechanical agitator or stirrer such as a shaft equipped with paddles or helical blades, or any other device designed to prevent the balling up of the mass during the mixing operation. This mixer is preferably heated either by the waste gases from a furnace or by the direct heat from a suitable furnace whichmay be located beneath the same. When the mixer containing the desired quantity of dry precipitated calcium carbonate, say one ton gross for example, has been thoroughly heated about 100 pounds of a suitable grease or oil mixture, such as for example melted tallow, stearic acid, melted degras grease or other melted fatty acid suitable for the purpose, is sprayed over the hot mass while same, in lieu of melting the same; then thIS thin mixture is sprayed on to the heated dry carbonate. 7 The heating is continued until substantially all of the moisture has been vaporized and until the test sample when tested on the surface of the water will emain floating thereon despite continued and repeated jarring of the container, such as.

for example a test tube, in which the test is the agitating devices are maintaining the same in a thoroughly be obtained if a hght solvent,

made in an effort to dislodge the floating material on the surface in order to cause the same to sink.

In lieu of employing precipitated calcium carbonate in a substantially dry condition, I may also utilize the wet cake of precipitated calcium carbonate obtained from the filter press in various operations wherein the same is produced in a precipitated form, such for example as in the production of magnesia from Dolomite rock. Such filter press cake, which ordinarily will contain around of water, is first introduced in the centrifuge wherein a substantial percentage of the water is removed and a product containing about fifty per cent of precipitated calcium carbonate and fifty per cent of water is obtained. This latter mass is then placed in the mixer aforesaid, and the grease, oil or fatty acid employed is directlyintroduced into the mixture without first heating the same or dissolving the same in a volatile solvent. and after such introduction the heat is applied to the mixture. The water is of course first vaporized from the mixture and the grease or oil vehicle is thoroughly distributed throughout the mass during such vaporization period and as soon as the water has been substantially driven off the thorough and intimate penetration of the grease or oil vehicle throughout the mass is effected in the same manner as when a dry precipitated calcium carbonate base is employed as above described. \Vhile this wet process requires a longer time for the production of a batch of the finished parting than does the above described dry process, nevertheless where' the precipitated calcium carbonate is available in the form of a wet cake it eliminates the necessity and the expense of drying the same before its introduction into the mixture besides making it pos- .sible to maintain a more thorough distribution of the grease or oil vehiclethroughoutthe batch, as not only is the heating and mixing operation of greater duration but also the wet, putty-like mass of this extremely light material tends to offer more resistance to the agitating devices, with the consequence that such vehicle becomes wrapped up more thoroughly and incorporated more effectively with the calcium carbonate base.

In order to further improve the product obtained as aforesaid and particularly to reduce to a minimum the tendency of the same to dust, which not only avoids waste but renders the air in the immediate vicinity of the molder better for inhalation into the lungs of the latter; and also in order to enhance the parting function of the material, especially in those cases where the molding sand is hot and steaming, I incorporate with the product produced by either of the methods above described a proportion of 1 to 5 per cent of herosene oil prior to the removal of the same from the mixer but after the batch in such mixer has been cooled to a point which is but slightly above the vaporizing point of the oil. Preferably such kerosene oil is sprayed into such batch, and the agitation is continued in the mixer until the kerosene oil has been thoroughly distributed throughout the mass. If desired, in lieu of such kerosene oil I may substitute for part or all of the kerosene oil other mineral or organic liquid solvents as gasolene or benzol (coal tar benzine), and may incorporate'with such solvents varying percentages, preferably about 25%, of heavier hydrocarbons as petroleum residues, gas oil, waste, crank case oil from automobiles, or like compounds capable of imparting slippery properties to the parting.

Not only does the aforesaid treatment with kerosene or a mixture of kerosene and heavier hydrocarbon sufficiently reduce the dusting tendency of the finished product, but it also greatly facilitates the clean separation or parting of the pattern from the sand surface of the mold by virtue of the fact that it renders the finished product unetuous,-that is, it imparts thereto a greasy or soapy feel or slip and thus prevents the sticking of such product to the pattern as well as the consequent sticking of the sand to the latter. Owing to the natural dry, powdery consistency of calcium carbonate and its entire absence of unctuous property, as well as because of its high absorptive properties, this subsequent treatment to render the same unctuous is decidedly advantageous, as calcium carbonate is because of its high absorptive properties and lightness an ideal base for parting.

Because of the high absorptiveness of the carbonate base it is possible to render the same far more impervious and repellent to moisture than bases heretofore commonly employed, as Tripoli, burnt clay, fossil meal and the like, and as a consequence my improved product made as above described, particularly when employing either raw wool grease (degras) or refined wool grease (lanolin) as the waterproofing ingredient in the first step of the treatment, will remain fioating on water for weeks and even months without settling, whereas parting products made from the other bases aforesaid sink usually within thirty-six to forty-eight hours When distributed on the surface of water. Furthermore, owing to its extreme fineness, which degree of fineness can only be approximated when employing silicious materials at a prohibitive expense for grinding the same, my improved product has a much greater covering or hiding power (i. e., pigment value) when dusted over the pattern and on the sand surface of a mold between the cope and the drag, with the consequence that notwithstanding its extremely light weight virtually the same volume or evcnless of my improved product will sufiice for dusting the pattern and the sand surface as is now required with a much heavier silicious base parting, with herein described treatment has been found the consequence that my improved product to be quite satisfactory.

is two to three times as efficient as other part- My iniprovet parting compound, whether ing products now on the market. made from precipitated calcium carbonate 5 Althoughl much prefer calcium carbonate as a base or from thoroughly calcined non- 70 as a base, my experiments have also led to setting gypsum (CaSOQ, 1s remarka ly the discovery that thoroughly calcined gyplight. The standard sugar barrel, the consum or precipitated calcium sulphate in such tents of which approximate six cubic feet,

condition that it has lost its tendency to set when filled with the same and loosely packed when mixed with water will also, when sub- (i. e.. not packed with a mechanical packer) stituted for the aforesaid calcium carbonate weighing somewhat less than 150 pounds, and

and used in substantially the same proporwhen mechanically packed with a mechaniti ns a h alci m carbonat in the ab ve cal packer of the type provided with helical described methods of making parting, proflights, weighing somewhat less than 200 duce a very satisfactory parting and accor pounds. inglv non-setting calcium sulphate is also While I prefer to employ kerosene having included within the scope of certain of the afiashing point not under 150 C. for the secappended claims as a base material 0 the ond stage of the treatment either alone or in parting covered thereby. Preferably in oradmixture with other oil vehicles, as well as 2 der to obtain a non-setting gypsum it is necemploying the same in the first stage of the essary to heat, the same to approximately 500 PXOCQSS in tlIO SG cases where it volatile SOlVGIlt (3., for as is well known the partial de-hydrais employed to dissolve the greasy material, tion of gypsum results in the production of nevertheless other solvents such as solvent plaster of Paris which latter product 15 unn phtha, gasolene and the like may, if proper 25 suitable for the production of parting owing precautions against fire are taken, be emto its well-known setting properties whe ployed in lieu thereof, for the purpose 0 i d ith water. dissolving or thinning the grease or oil mayvhfl 1 h d ib d th l y nt, of terial employed in the first or second stages 100 pounds of degras grease, either dissolved of he process.

in a suitable solvent or employed as such or Having thus described my invention, 1

in a melted condition, to one ton of calcium claim:

carbonate on a dry basis, or in other words, 5 1- A parting Composition for molds of er cent by weight of the base, it is obvious foundries,comprising a finely divided precipithat other percentages varying from two per tated alkaline-earth metal carbonate consticent to not over ten per cent may b mtuting its major ingredients, the same being ployed without entirely losing the benefits of impregnated with a very small percentage of my invention. as the chief consideration in an organic waterproofing substance, said comso far as the amount. of waterproofing subposition being extremely light and capable of stance is concerned is to have a sufficient floating on water without settling for long 4 quantity thereof to impart the necessary periods and in excess of fourteen days.

waterproofing properties while avoiding such 2-. A parting composition for molds of an excess as would render the resultant partfoundries, comprising a finely precipitated ing objectionably sticky, to the'extent that calcium carbonate constituting its major inthe same would tend to adhere to the pattern gredient, the same being impregnated with a 4 as well as tend to cause balling of the very small percentage of an organic waterduce proofing substance, said composition being Likewise the proportions of kerosene oil extremely light and capable of floating on employed in the final stage of the process water without settling for long periods and in might. vary within wide limits, and if deexcess of fourteen days.

5 sired the same may be entirely s bstituted 3. A molding composition for foundries.

' by light lubricating oil or other oily comcomprising afinely divided precipitated alka pound adapted to impart the necessary unctuline-earth metal carbonate constituting its ous properties to the finished product, but. the major ingredient, the same being impregnated ercentage of such kerosene oi or oily mawith a very small percentage of an organic 55 terial substituted therefor shall not be less waterproofing substance, said composition bethan one-half per cent, preferably not more ing extremely light and capable of floating on than seven per cent, if the benefits thereof water without settling for long periods and in are to be properly secured. However, wit excess of fourteen days, the partlcles having in the scope of certain of the appended claims a superficial coating of such waterproofing 60 is included a parting product which has substances to an extent sufficient to impart not been subjected to the second stage of thereto a decidedly greasy slip or feel andb treatment. with gasoline or like compound ing substantially non-dusting.

capable of imparting unctuous properties to 4. A parting composition for molds of the compound, as for some purposes aproduct foundries, comprising a finely precipitated 65 made in accordance with the first stage of the calcium carbonate constituting its major in- "gredient, the same being impregnated with a very small percentage of wool grease, said composition being extremely light and capale of floating on water without settling for long periods and in excess of fourteen days. a

5. A parting composition for molds of foundries, comprising a finely precipitated calcium carbonate constituting its major ingredient, the same being impregnated with about 5% of wool grease, said composition being extremely light and ca able of floating on water without settlin fiir long periods and in excess of fourteen ays.

6. A parting composition for molds of foundries, comprising a finely precipitated calcium compound constituting its major ingredient, the same being impregnated with a very small percentage, and not exceeding ten percent, of an organic Waterproofing substance, said composition being extremely light and capable of floating on Water without settling for long periods and in excess of fourteen days.

. 7. The method of making a parting com osition for molds of foundries which consists in impregnating an aqueous mass of a preci itated alkaline-earth metal carbonate base with a small percentage,

and then subjecting the mass while agitating the same to heat sufficient to evaporate substantially all of the moisture and then continuing the heating operation during continued agitation thereof to a higher temperature to effect the thorough and homogeneous penetration of the waterproofing substance into the base. x

8. The method of making a arting composition for molds of foundries w ich consists in impregnating an aqueous mass of a precipitated alkaline-earth metal carbonate base with a small percentage, and not exceeding ten per cent, of an organic waterproofin substance and then subjecting the mass Whi e agitating the same to heat sufficient to evaporate substantially all of the moisture and then continuing the heating operation during continned agitation thereof to a high temperature, and sufficient to effect the thorough and homogeneous penetration of the waterproofing substance into the base.

9. The method of making a parting comp0-' sition for molds of foundries which consists in impregnating an aqueous mass of a preci 1'- tated alkaline-earth metal carbonate base with a small percentage, and not exceeding ten per cent, of an organic waterproofing substance and then subjecting the mass while agitating the same to heat sufficient to evaporate substantially all of the moisture and then continuing the heating operation during continued agitation thereof to a high temperature, of at least 200 C.

10. The method of making position for molds of foun a partin comries whic consubstance evaporate substantially all then continuing the heating operation during continued agitation thereof to a higher temperature to effect the thorough and homo-,

geneous penetration of the waterproofing substance into the base, and then allowing the mass to cool and distributing throughout the mass a small percentage of volatile hydrocarbon solvent while the temperature of said mass is still substantially above the vaporizing point of such solvent.

11. The method of making a partin composition for molds of foundries whici consists in impregnating an aqueous mass of a precipitated alkaline-earth metal carbonate base with a small percentage, and not exceeding ten per cent, of an organic waterproofing substance and then subjecting the mass while agitating the same-to heat sufficient to evaporate substantially all of the moisture, then continuing the heating operation during con-' and not exceeding ten per t' cent, of an organic waterproofin 3O penetration of the Waterproofing su stance into the base, and then s raying the mass after the partial cooling o same with small percentage of a mixture of kerosene and heavier hydrocarbons.

12. The method of making a partin position for molds of foundries whic sists in impregnating an aqueous mass recipitated alkaline-earth metal carbonate ase with a small percentage, and not exceedin ten per cent, of an organic waterproofing substance and then subjecting the mass while agitating the same to heat sufiicient to evaporate substantially all of the moisture, then continuing the heating operation during con tinued agitation thereof to a higher temperature toeffect the thorough and homo eneous penetration of the waterproofing su stance into the base, and then distributing throughout the mass while still hot small percentage of a hydrocarbon liquid adapted to substantially eliminate objectionable dusting of the finished product when in use and to impart a greasy slip to the particles thereof wherein in use the sticking of the same to the pattern, with the consequent sticking of the same to the latter, is prevente 13. In the manufacture of a molding composition for foundries, the step which consists in superficially coating a grease impregnated highly absorbent, fluffy, water-insoluble salt of calcium with a small percentage, and not exceeding seven per cent, of an oily subthereof and to comstance to allay the dusting render the same unctuous.

14. In the manufacture of a. molding comof a percentage, and not exceedof the moisture,

position for foundries, the step which consists in spraying a base comprisng calcium carbonate, homogeneously impregnated with not exceeding seven per cent of a mineral oil. degras grease, with a small percentage, and. Signed at New York, in. the county of New 5 not exceeding seven per cent, of kerosene. York and State of New York, this 14th day of 15. In the manufacture of a molding com- July, 1925. position for foundries, the step which consists in spraying a base comprising calcium BENJAMIN F. WALLACE.

carbonate, homogeneously impregnated with degras grease, with a small percentage, and 1